Accelerated Antarctic ice loss from satellite gravity measurements

Accurate quantification of Antarctic ice-sheet mass balance and its contribution to global sea-level rise remains challenging, because in situ measurements over both space and time are sparse. Satellite remote-sensing data of ice elevations and ice motion show significant ice loss in the range of -31 to -196Gtyr-1 in West Antarctica in recent years, whereas East Antarctica seems to remain in balance or slightly gain mass, with estimated rates of mass change in the range of -4 to 22Gtyr-1. The Gravity Recovery and Climate Experiment (GRACE) offers the opportunity of quantifying polar ice-sheet mass balance from a different perspective. Here we use an extended record of GRACE data spanning the period April 2002 to January 2009 to quantify the rates of Antarctic ice loss. In agreement with an independent earlier assessment, we estimate a total loss of 190+/-77Gtyr-1, with 132+/-26Gtyr-1 coming from West Antarctica. However, in contrast with previous GRACE estimates, our data suggest that East Antarctica is losing mass, mostly in coastal regions, at a rate of -57+/-52Gtyr-1, apparently caused by increased ice loss since the year 2006.